Restrict treee copiers with default arguments to trees with more than 2 elements.

It's not really an abbreviation to do it for trees with fewer elements and it leads
to unncessessary syntactic variation.

Author: odersky

src/dotty/tools/dotc/ast/Desugar.scala

@@ -504,8 +504,8 @@ object desugar {
    */
   def block(tree: Block)(implicit ctx: Context): Block = tree.expr match {
     case EmptyTree =>
-      cpy.Block(tree)(
-        expr = unitLiteral withPos (if (tree.stats.isEmpty) tree.pos else tree.pos.endPos))
+      cpy.Block(tree)(tree.stats,
+        unitLiteral withPos (if (tree.stats.isEmpty) tree.pos else tree.pos.endPos))
     case _ =>
       tree
   }

src/dotty/tools/dotc/ast/Trees.scala

@@ -433,7 +433,7 @@ object Trees {
   case class Select[-T >: Untyped] private[ast] (qualifier: Tree[T], name: Name)
     extends RefTree[T] {
     type ThisTree[-T >: Untyped] = Select[T]
-    def withName(name: Name)(implicit ctx: Context): untpd.Select = untpd.cpy.Select(this)(name = name)
+    def withName(name: Name)(implicit ctx: Context): untpd.Select = untpd.cpy.Select(this)(qualifier, name)
   }
 
   class SelectWithSig[-T >: Untyped] private[ast] (qualifier: Tree[T], name: Name, val sig: Signature)
@@ -620,7 +620,7 @@ object Trees {
   case class SelectFromTypeTree[-T >: Untyped] private[ast] (qualifier: Tree[T], name: Name)
     extends RefTree[T] {
     type ThisTree[-T >: Untyped] = SelectFromTypeTree[T]
-    def withName(name: Name)(implicit ctx: Context): untpd.SelectFromTypeTree = untpd.cpy.SelectFromTypeTree(this)(name = name)
+    def withName(name: Name)(implicit ctx: Context): untpd.SelectFromTypeTree = untpd.cpy.SelectFromTypeTree(this)(qualifier, name)
   }
 
   /** left & right */
@@ -666,7 +666,7 @@ object Trees {
     extends NameTree[T] with DefTree[T] with PatternTree[T] {
     type ThisTree[-T >: Untyped] = Bind[T]
     override def envelope: Position = pos union initialPos
-    def withName(name: Name)(implicit ctx: Context): untpd.Bind = untpd.cpy.Bind(this)(name = name)
+    def withName(name: Name)(implicit ctx: Context): untpd.Bind = untpd.cpy.Bind(this)(name, body)
   }
 
   /** tree_1 | ... | tree_n */
@@ -1094,24 +1094,24 @@ object Trees {
       }
 
       // Copier methods with default arguments; these demand that the original tree
-      // is of the same class as the copy
-
-      def Select(tree: Select)(qualifier: Tree = tree.qualifier, name: Name = tree.name): Select =
-        Select(tree: Tree)(qualifier, name)
-      def Super(tree: Super)(qual: Tree = tree.qual, mix: TypeName = tree.mix): Super =
-        Super(tree: Tree)(qual, mix)
-      def Apply(tree: Apply)(fun: Tree = tree.fun, args: List[Tree] = tree.args): Apply =
-        Apply(tree: Tree)(fun, args)
-      def TypeApply(tree: TypeApply)(fun: Tree = tree.fun, args: List[Tree] = tree.args): TypeApply =
-        TypeApply(tree: Tree)(fun, args)
-      def Typed(tree: Typed)(expr: Tree = tree.expr, tpt: Tree = tree.tpt): Typed =
-        Typed(tree: Tree)(expr, tpt)
-      def NamedArg(tree: NamedArg)(name: Name = tree.name, arg: Tree = tree.arg): NamedArg =
-        NamedArg(tree: Tree)(name, arg)
-      def Assign(tree: Assign)(lhs: Tree = tree.lhs, rhs: Tree = tree.rhs): Assign =
-        Assign(tree: Tree)(lhs, rhs)
-      def Block(tree: Block)(stats: List[Tree] = tree.stats, expr: Tree = tree.expr): Block =
-        Block(tree: Tree)(stats, expr)
+      // is of the same class as the copy. We only include trees with more than 2 elements here.
+
+      //def Select(tree: Select)(qualifier: Tree = tree.qualifier, name: Name = tree.name): Select =
+      //  Select(tree: Tree)(qualifier, name)
+      //def Super(tree: Super)(qual: Tree = tree.qual, mix: TypeName = tree.mix): Super =
+      //  Super(tree: Tree)(qual, mix)
+      //def Apply(tree: Apply)(fun: Tree = tree.fun, args: List[Tree] = tree.args): Apply =
+      //  Apply(tree: Tree)(fun, args)
+      //def TypeApply(tree: TypeApply)(fun: Tree = tree.fun, args: List[Tree] = tree.args): TypeApply =
+      //  TypeApply(tree: Tree)(fun, args)
+      //def Typed(tree: Typed)(expr: Tree = tree.expr, tpt: Tree = tree.tpt): Typed =
+      //  Typed(tree: Tree)(expr, tpt)
+      //def NamedArg(tree: NamedArg)(name: Name = tree.name, arg: Tree = tree.arg): NamedArg =
+      //  NamedArg(tree: Tree)(name, arg)
+      //def Assign(tree: Assign)(lhs: Tree = tree.lhs, rhs: Tree = tree.rhs): Assign =
+      //  Assign(tree: Tree)(lhs, rhs)
+      //def Block(tree: Block)(stats: List[Tree] = tree.stats, expr: Tree = tree.expr): Block =
+      //  Block(tree: Tree)(stats, expr)
       def If(tree: If)(cond: Tree = tree.cond, thenp: Tree = tree.thenp, elsep: Tree = tree.elsep): If =
         If(tree: Tree)(cond, thenp, elsep)
       def Closure(tree: Closure)(env: List[Tree] = tree.env, meth: Tree = tree.meth, tpt: Tree = tree.tpt): Closure =
@@ -1120,20 +1120,20 @@ object Trees {
         Match(tree: Tree)(selector, cases)
       def CaseDef(tree: CaseDef)(pat: Tree = tree.pat, guard: Tree = tree.guard, body: Tree = tree.body): CaseDef =
         CaseDef(tree: Tree)(pat, guard, body)
-      def Return(tree: Return)(expr: Tree = tree.expr, from: Tree = tree.from): Return =
-        Return(tree: Tree)(expr, from)
+      //def Return(tree: Return)(expr: Tree = tree.expr, from: Tree = tree.from): Return =
+      //  Return(tree: Tree)(expr, from)
       def Try(tree: Try)(expr: Tree = tree.expr, handler: Tree = tree.handler, finalizer: Tree = tree.finalizer): Try =
         Try(tree: Tree)(expr, handler, finalizer)
-      def SelectFromTypeTree(tree: SelectFromTypeTree)(qualifier: Tree = tree.qualifier, name: Name = tree.name):
-        SelectFromTypeTree = SelectFromTypeTree(tree: Tree)(qualifier, name)
-      def RefinedTypeTree(tree: RefinedTypeTree)(tpt: Tree = tree.tpt, refinements: List[Tree] = tree.refinements):
-        RefinedTypeTree = RefinedTypeTree(tree: Tree)(tpt, refinements)
-      def AppliedTypeTree(tree: AppliedTypeTree)(tpt: Tree = tree.tpt, args: List[Tree] = tree.args): AppliedTypeTree =
-        AppliedTypeTree(tree: Tree)(tpt, args)
-      def TypeBoundsTree(tree: TypeBoundsTree)(lo: Tree = tree.lo, hi: Tree = tree.hi): TypeBoundsTree =
-        TypeBoundsTree(tree: Tree)(lo, hi)
-      def Bind(tree: Bind)(name: Name = tree.name, body: Tree = tree.body): Bind =
-        Bind(tree: Tree)(name, body)
+      //def SelectFromTypeTree(tree: SelectFromTypeTree)(qualifier: Tree = tree.qualifier, name: Name = tree.name):
+      //  SelectFromTypeTree = SelectFromTypeTree(tree: Tree)(qualifier, name)
+      //def RefinedTypeTree(tree: RefinedTypeTree)(tpt: Tree = tree.tpt, refinements: List[Tree] = tree.refinements):
+      //  RefinedTypeTree = RefinedTypeTree(tree: Tree)(tpt, refinements)
+      //def AppliedTypeTree(tree: AppliedTypeTree)(tpt: Tree = tree.tpt, args: List[Tree] = tree.args): AppliedTypeTree =
+      //  AppliedTypeTree(tree: Tree)(tpt, args)
+      //def TypeBoundsTree(tree: TypeBoundsTree)(lo: Tree = tree.lo, hi: Tree = tree.hi): TypeBoundsTree =
+      //  TypeBoundsTree(tree: Tree)(lo, hi)
+      //def Bind(tree: Bind)(name: Name = tree.name, body: Tree = tree.body): Bind =
+      //  Bind(tree: Tree)(name, body)
       def UnApply(tree: UnApply)(fun: Tree = tree.fun, implicits: List[Tree] = tree.implicits, patterns: List[Tree] = tree.patterns): UnApply =
         UnApply(tree: Tree)(fun, implicits, patterns)
       def ValDef(tree: ValDef)(mods: Modifiers = tree.mods, name: TermName = tree.name, tpt: Tree = tree.tpt, rhs: Tree = tree.rhs): ValDef =
@@ -1144,12 +1144,12 @@ object Trees {
         TypeDef(tree: Tree)(mods, name, rhs, tparams)
       def Template(tree: Template)(constr: DefDef = tree.constr, parents: List[Tree] = tree.parents, self: ValDef = tree.self, body: List[Tree] = tree.body): Template =
         Template(tree: Tree)(constr, parents, self, body)
-      def Import(tree: Import)(expr: Tree = tree.expr, selectors: List[untpd.Tree] = tree.selectors): Import =
-        Import(tree: Tree)(expr, selectors)
-      def PackageDef(tree: PackageDef)(pid: RefTree = tree.pid, stats: List[Tree] = tree.stats): PackageDef =
-        PackageDef(tree: Tree)(pid, stats)
-      def Annotated(tree: Annotated)(annot: Tree = tree.annot, arg: Tree = tree.arg): Annotated =
-        Annotated(tree: Tree)(annot, arg)
+      //def Import(tree: Import)(expr: Tree = tree.expr, selectors: List[untpd.Tree] = tree.selectors): Import =
+      //  Import(tree: Tree)(expr, selectors)
+      //def PackageDef(tree: PackageDef)(pid: RefTree = tree.pid, stats: List[Tree] = tree.stats): PackageDef =
+      //  PackageDef(tree: Tree)(pid, stats)
+      //def Annotated(tree: Annotated)(annot: Tree = tree.annot, arg: Tree = tree.arg): Annotated =
+      //  Annotated(tree: Tree)(annot, arg)
     }
 
     abstract class TreeMap(val cpy: TreeCopier = inst.cpy) {

src/dotty/tools/dotc/transform/Nullarify.scala

@@ -72,7 +72,7 @@ class Nullarify extends MiniPhaseTransform with InfoTransformer {
     val MethodType(_, formals) = methType(funType, tree.fun)
 
     val args1 = tree.args.zipWithConserve(formals)(transformArg)
-    cpy.Apply(tree)(args = args1) withType nullarify(tree.tpe)
+    cpy.Apply(tree)(tree.fun, args1) withType nullarify(tree.tpe)
   }
 
   /** Insert () or .apply() if the term refers to something that was converted to a

src/dotty/tools/dotc/transform/UncurryTreeTransform.scala

@@ -23,7 +23,7 @@ class UncurryTreeTransform extends MiniPhaseTransform with InfoTransformer {
         showType
         ctx.atNextPhase(showType(_))
         showType
-        cpy.Apply(tree)(args = args ++ tree.args)
+        cpy.Apply(tree)(tree.fun, args ++ tree.args)
       case _ => tree
     }}
 

src/dotty/tools/dotc/typer/ReTyper.scala

@@ -32,13 +32,13 @@ class ReTyper extends Typer {
   override def typedSelect(tree: untpd.Select, pt: Type)(implicit ctx: Context): Tree = {
     assert(tree.hasType)
     val qual1 = typed(tree.qualifier, AnySelectionProto)
-    untpd.cpy.Select(tree)(qualifier = qual1).withType(tree.typeOpt)
+    untpd.cpy.Select(tree)(qual1, tree.name).withType(tree.typeOpt)
   }
 
   override def typedSelectFromTypeTree(tree: untpd.SelectFromTypeTree, pt: Type)(implicit ctx: Context): SelectFromTypeTree = {
     assert(tree.hasType)
     val qual1 = typed(tree.qualifier, AnySelectionProto)
-    untpd.cpy.SelectFromTypeTree(tree)(qualifier = qual1).withType(tree.typeOpt)
+    untpd.cpy.SelectFromTypeTree(tree)(qual1, tree.name).withType(tree.typeOpt)
   }
 
   override def typedLiteral(tree: untpd.Literal)(implicit ctc: Context): Literal =
@@ -50,7 +50,7 @@ class ReTyper extends Typer {
   override def typedBind(tree: untpd.Bind, pt: Type)(implicit ctx: Context): Bind = {
     assert(tree.hasType)
     val body1 = typed(tree.body, pt)
-    untpd.cpy.Bind(tree)(body = body1).withType(tree.typeOpt)
+    untpd.cpy.Bind(tree)(tree.name, body1).withType(tree.typeOpt)
   }
 
   override def localDummy(cls: ClassSymbol, impl: untpd.Template)(implicit ctx: Context) = impl.symbol